About 84% of people who go vegetarian or vegan eventually return to eating animal products, according to a large study by the animal advocacy research organization Faunalytics. More than half quit within the first year, and a third don’t make it past three months. The reasons fall into a few overlapping categories: social friction, physical discomfort, nutritional gaps, and the sheer mental load of maintaining a restrictive diet in a world that doesn’t make it easy.
Most People Quit Early
The dropout curve is steep. Roughly 53% of people who try a vegan or vegetarian diet abandon it in under a year. A full third give up within 90 days. That timeline matters because it suggests the initial adjustment period is where most people hit a wall. The first few months involve the steepest learning curve: figuring out what to cook, how to eat out, how to get enough of the right nutrients, and how to handle the social dynamics. People who survive that window are far more likely to stick with it long term.
Social Pressure Is Relentless
Food is social glue, and veganism pulls against that in ways people don’t anticipate. In qualitative research on plant-based eating, participants consistently described feeling excluded at restaurants, exhausted from explaining their choices, and reluctant to be “that person” who needs a special menu. One participant put it simply: they wouldn’t want to miss out on social events because of dietary restrictions.
Relationships add another layer. Partners, families, and roommates who eat differently create daily friction, even when everyone is supportive in theory. One participant in the same research noted they became less strict about plant-based eating after their partner decided to stop being vegan. When the person you share meals with changes direction, it takes real effort to hold your own course. Cooking two separate dinners every night, negotiating holiday meals, fielding questions from relatives: these small stresses compound over months and years.
There’s also an identity cost. Announcing you’re vegan invites opinions, jokes, and debates. Some people find that energizing at first but draining over time, especially if they started the diet quietly and weren’t looking for a lifestyle label.
Digestive Problems in the Transition
A sudden jump in fiber intake is one of the most common physical complaints new vegans face, and it hits right in that critical first few months. Beans, lentils, whole grains, and vegetables are the backbone of a vegan diet, and they’re all rich in fiber that gut bacteria ferment into gas. That fermentation produces carbon dioxide, hydrogen, and methane, which leads to bloating, cramping, and flatulence.
The problem isn’t just gas production. Dietary fiber can also slow the movement of gas through the intestines, trapping it longer and making bloating feel worse. Research from the OmniHeart trial found that switching from a typical low-fiber American diet to a high-fiber one significantly increased bloating. The effect was especially pronounced with plant-based protein sources like beans, legumes, and soy, which are rich in oligosaccharides, a type of highly fermentable fiber that produces more gas than other fiber types.
For most people, the gut adjusts within a few weeks as the microbiome shifts. But if you don’t know that, a week of painful bloating after going vegan can feel like your body is rejecting the diet. Gradual transitions work much better than overnight switches, yet many new vegans go all-in immediately.
Vitamin B12 and Nutritional Gaps
Vitamin B12 is the most well-documented nutritional risk of a vegan diet. B12 is found almost exclusively in animal products, and without deliberate supplementation, deficiency is nearly inevitable. Studies estimate that 50 to 70% of vegans have subnormal B12 levels. One European comparison found outright deficiency in 92% of vegans, compared to 11% of omnivores.
The tricky part is that B12 deficiency develops slowly and its symptoms are easy to misattribute. Fatigue, trouble concentrating, insomnia, anxiety, and low mood can all stem from inadequate B12. People experiencing these symptoms on a vegan diet may not connect them to nutrition at all. They just feel worse than they used to and conclude the diet isn’t working for them. In more severe cases, deficiency can cause anemia, nerve damage, and cognitive impairment.
The fix is straightforward: a B12 supplement or fortified foods like nutritional yeast, plant milks, and certain cereals. But many new vegans don’t realize supplementation is non-negotiable, not optional. Without clear guidance up front, people drift into deficiency, feel terrible, and quit, often blaming veganism itself rather than one missing nutrient.
The Perception That It Costs More
Cost is frequently cited as a barrier to plant-based eating, but the data tells a different story. A Portuguese study of over 1,000 consumers found that vegans actually spent the least on food of any dietary group. Omnivores reported average weekly grocery spending of about €76, while vegans averaged around €48. The gap held for both home-cooked and restaurant meals.
The confusion comes from the visibility of expensive specialty products. Plant-based meat substitutes, fancy nut cheeses, and organic prepared meals carry premium price tags, and the plant-based substitute market has grown rapidly, reaching billions in annual sales. When people think “vegan food,” they picture a $7 package of plant-based burger patties rather than a bag of dried lentils. The staples of a vegan diet (beans, rice, oats, tofu, seasonal vegetables) are among the cheapest foods in any grocery store. But the perception of high cost discourages people from starting and gives those who are already struggling a convenient reason to stop.
Hunger and Feeling Unsatisfied
A common complaint among former vegans is that they never felt full. The science here is more nuanced than the complaint suggests. A large study tracking over 16,300 individual meal entries found that plant-based meals and meat-based meals produced essentially the same drop in hunger after eating. When researchers controlled for macronutrients (matching protein, fat, and carbs), plant-based meals actually produced slightly greater satiety.
So the issue isn’t that plant food can’t fill you up. It’s that many new vegans don’t eat enough calories or enough protein-dense foods. A salad that would have been a side dish becomes the whole meal. Snacking on fruit replaces calorie-dense options. Without understanding how to build a complete plate (combining grains with legumes, adding nuts and seeds, using calorie-dense ingredients like avocado and tahini), people end up chronically under-eating. The hunger is real, but it reflects poor meal construction rather than an inherent problem with plant-based food.
The Mental Load of Restriction
Veganism requires constant decision-making. Reading labels, checking ingredients at restaurants, planning meals ahead, carrying snacks in case nothing is available. For some people, this vigilance becomes exhausting. For others, it can tip into something more concerning.
Research on eating patterns shows a significant overlap between restrictive diets and disordered eating. More than half of patients with eating disorders report adopting some form of vegetarian diet after the onset of their disorder. Two-thirds of people with a history of eating disorders said their choice of vegetarianism was connected to their condition because it gave them a socially acceptable way to limit food intake and maintain a sense of control. This doesn’t mean veganism causes eating disorders, but the structure of a highly restrictive diet can attract people who are vulnerable to disordered patterns, or push people toward unhealthy rigidity over time.
Even for people without any predisposition to eating disorders, the cognitive burden of constant food monitoring wears thin. Decision fatigue is real. After months of scrutinizing every meal, some people simply run out of willpower and return to eating whatever is easiest and most available.
Why Some Vegans Stick With It
The 16% who maintain a vegan diet long term tend to share a few traits. They usually have a strong ethical motivation rather than a purely health-based one. They’ve learned to cook well and enjoy the food rather than treating it as a sacrifice. They’ve built social support, whether through vegan friends, online communities, or a partner who eats the same way. And they’ve addressed the practical basics: they supplement B12, eat enough calories, and have go-to meals for busy days when planning isn’t possible.
The high quit rate isn’t evidence that veganism is nutritionally unsustainable. It’s evidence that any major dietary change is hard to maintain without preparation, support, and realistic expectations about the adjustment period. Most people who quit do so not because the diet failed them biologically, but because the combination of social friction, digestive discomfort, nutritional blind spots, and mental fatigue became more than they were willing to manage.